Add the devices to be used for development in ‘Certificates’
In Macintosh HD > Applications > Utilities > Keychain Access
Menu > Keychain Access > Preferences > Certificates > set Online Certificate Status Protocol (OSCP) and Certificate Revocation List (CRL) to “Off”.
Menu > Keychain Access > Certificate Assistant > Request a Certificate from a Certificate Authority.
‘User Email Address’ and ‘Common Name’ must match the registered iPhone Developer info
CA (Certificate Authority) Email Address: Not required. (The ‘Required’ message will be auto removed)
Request is: ‘Saved to Disk’
Let me specify key pair information: Checked
Specify file name and click Save.
Key Size: 2048 bits
Press Continue and the certificate request will be created. After a few moments refreshing the browser will have the certificate available to download.
Using Issued Certificate
Download the WWDR Intermediate Certificate. Then double-click the downloaded cert to launch Keychain Access and install (the default Keychain: Login is fine).
Download the issued Developer Identity Certificate. Then double-click the downloaded cert to launch Keychain Access and install(the default Keychain: Login is fine).